COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF UNS C14500 TELLURIUM COPPER FASTENERS
UNS C14500, commonly known as Tellurium Copper, is a highly specialized "free-machining" copper alloy. Pure copper is notoriously "gummy" and difficult to thread cleanly, often leading to tool wear and torn threads. By precision-alloying pure copper with a small, controlled amount of Tellurium (0.40% – 0.70%), the metallurgical matrix is altered to produce short, brittle chips during CNC machining. This allows for the rapid manufacturing of highly complex fastener geometries with razor-sharp thread profiles.
The true engineering triumph of C14500 is its retention of electrical performance. While standard strengthening alloys (like bronzes or brasses) destroy copper's conductivity, Tellurium Copper maintains a phenomenal 90% to 93% IACS conductivity. This makes C14500 fasteners the undisputed benchmark for high-amperage electrical connectors, switchgear terminals, and electromechanical assemblies requiring both complex machining and massive current-carrying capacity.
■ Product Overview & Specifications
| Material Classification | Free-Machining Copper (Tellurium Alloyed) |
|---|---|
| UNS Designation | C14500 |
| Microstructure | Alpha Copper with Insoluble Copper Telluride (Cu₂Te) Inclusions |
| Magnetic State | Completely Non-Magnetic |
| Density | 8.94 g/cm³ (0.323 lb/in³) |
| Size Range | Metric: M2 to M36 | Imperial: #4 to 1-1/2" |
| Primary Attribute | Machinability Rating of 85% (vs. Pure Copper at 20%) |
■ Proprietary Datasheet Download (GATED)
UNS C14500 Tellurium Copper — Complete Technical Datasheet
Contains detailed thread dimensional tolerances for high-speed CNC automated machining, maximum current-rating charts for standard fastener sizes, and thermal expansion coefficients for electromechanical joint design.
⬇ DOWNLOAD DATASHEET■ MTC Integration Section
Because Tellurium Copper is utilized in precision electrical infrastructure, verifying the exact Tellurium dispersion and Phosphorus deoxidation levels is critical to preventing hot-shortness. Every shipment is backed by verified mill traceability.
- EN 10204 Type 3.1: Validates the precise 0.40–0.70% Tellurium addition, strictly caps trace impurities, and certifies the final batch IACS electrical conductivity rating.
- EN 10204 Type 3.2: Available for aerospace, defense, or high-voltage grid infrastructure projects requiring third-party inspector verification.
■ Chemical Composition
The formulation of C14500 relies on the precise injection of Tellurium. Because Tellurium makes the copper susceptible to oxygen embrittlement during high-temperature processing, a microscopic amount of Phosphorus (P) is added to deoxidize the melt, ensuring structural integrity.
| Copper (Cu) + Silver (Ag) | Tellurium (Te) | Phosphorus (P) | Total Other Impurities |
|---|---|---|---|
| 99.90 Min* (Includes Te & P) | 0.40 – 0.70 | 0.004 – 0.012 | 0.10 Max |
■ Mechanical Properties
| Mechanical & Electrical Property | Hard Drawn Temper (Typical Fastener Limits) |
|---|---|
| Tensile Strength | 40,000 - 50,000 psi (275 - 345 MPa) |
| Yield Strength | 35,000 - 45,000 psi (240 - 310 MPa) |
| Machinability Rating | 85% (Relative to Free-Cutting Brass at 100%) |
| Electrical Conductivity | 90% - 93% IACS @ 20°C |
■ Equivalent Grades & Designations
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B301 (Rod, Bar, and Shapes) |
| Common Trade Names | Telco, Tellurium Copper, Alloy 145 |
| European Equivalent | EN CW118C / CuTeP (DIN 2.1546) |
| British Standard (BS) | BS 2874 C109 |
■ Applications & Industries
- Electrical Contacts & Relays: Small-diameter, highly threaded machine screws used inside complex electromechanical relays and power switches.
- Welding & Plasma Equipment: Specialized nozzles, torch tips, and retaining nuts where high thermal conductivity and precise internal threading are mandatory.
- Transformer Terminals: Custom machined studs and heavy-duty busbar hardware requiring superior surface finishes for maximum contact area.
■ Compatible Fastener Assemblies
| Mating Bolts/Machine Screws | Internal Threads (Nuts) | Washers |
|---|---|---|
| C14500 CNC Machined Screws & Studs | C14500 Precision Hex Nuts | C11000 or C14500 Flat Washers |
■ Torque & Installation Guidelines
Like all high-purity coppers, C14500 lacks the tensile strength of steel or bronze. Its supreme machinability means threads are incredibly smooth, which drastically reduces friction during installation. Overtorquing will easily strip the threads. Use calibrated torque wrenches and clean, dry installation practices unless otherwise specified.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) | Max Target Torque (ft-lbs) |
|---|---|---|---|
| #8 | 32 | 18 - 20 | ~ 1.5 |
| 1/4" | 20 | 48 - 55 | ~ 4.5 |
| 3/8" | 16 | 170 - 190 | ~ 15 |
| 1/2" | 13 | 400 - 430 | ~ 35 |
■ Frequently Asked Questions
1. How exactly does Tellurium make Copper easier to machine?
Pure copper is soft and ductile; when a cutting tool hits it, the metal stretches and tears, creating long, stringy, "gummy" chips that wrap around tooling and ruin thread finishes. The addition of Tellurium creates microscopic particles of Copper Telluride (Cu₂Te) throughout the metal. These particles act as intentional weak points (chip breakers), causing the metal to snap off cleanly into short chips during machining, leaving a polished, flawless thread behind.
2. Does the Tellurium addition ruin the electrical conductivity?
Surprisingly, no. While alloying elements like Zinc or Tin cause massive drops in conductivity (reducing it to 15-25% IACS), Tellurium is highly insoluble in the solid copper matrix. Because it doesn't heavily distort the atomic copper lattice, C14500 retains an exceptional 90% to 93% IACS, making the slight loss entirely worth the massive gain in manufacturing speed and precision.
3. Can C14500 Tellurium Copper be hot-forged like standard copper?
No. Tellurium Copper is generally considered "hot-short," meaning it becomes brittle and prone to cracking at high forging temperatures. C14500 fasteners are almost exclusively manufactured through cold working (cold heading) and high-speed CNC machining from solid bar stock.